1<p align="center"><img src="https://raw.githubusercontent.com/facebook/zstd/dev/doc/images/zstd_logo86.png" alt="Zstandard"></p> 2 3__Zstandard__, or `zstd` as short version, is a fast lossless compression algorithm, 4targeting real-time compression scenarios at zlib-level and better compression ratios. 5It's backed by a very fast entropy stage, provided by [Huff0 and FSE library](https://github.com/Cyan4973/FiniteStateEntropy). 6 7Zstandard's format is stable and documented in [RFC8878](https://datatracker.ietf.org/doc/html/rfc8878). Multiple independent implementations are already available. 8This repository represents the reference implementation, provided as an open-source dual [BSD](LICENSE) OR [GPLv2](COPYING) licensed **C** library, 9and a command line utility producing and decoding `.zst`, `.gz`, `.xz` and `.lz4` files. 10Should your project require another programming language, 11a list of known ports and bindings is provided on [Zstandard homepage](https://facebook.github.io/zstd/#other-languages). 12 13**Development branch status:** 14 15[![Build Status][travisDevBadge]][travisLink] 16[![Build status][CircleDevBadge]][CircleLink] 17[![Build status][CirrusDevBadge]][CirrusLink] 18[![Fuzzing Status][OSSFuzzBadge]][OSSFuzzLink] 19 20[travisDevBadge]: https://api.travis-ci.com/facebook/zstd.svg?branch=dev "Continuous Integration test suite" 21[travisLink]: https://travis-ci.com/facebook/zstd 22[CircleDevBadge]: https://circleci.com/gh/facebook/zstd/tree/dev.svg?style=shield "Short test suite" 23[CircleLink]: https://circleci.com/gh/facebook/zstd 24[CirrusDevBadge]: https://api.cirrus-ci.com/github/facebook/zstd.svg?branch=dev 25[CirrusLink]: https://cirrus-ci.com/github/facebook/zstd 26[OSSFuzzBadge]: https://oss-fuzz-build-logs.storage.googleapis.com/badges/zstd.svg 27[OSSFuzzLink]: https://bugs.chromium.org/p/oss-fuzz/issues/list?sort=-opened&can=1&q=proj:zstd 28 29## Benchmarks 30 31For reference, several fast compression algorithms were tested and compared 32on a desktop running Ubuntu 20.04 (`Linux 5.11.0-41-generic`), 33with a Core i7-9700K CPU @ 4.9GHz, 34using [lzbench], an open-source in-memory benchmark by @inikep 35compiled with [gcc] 9.3.0, 36on the [Silesia compression corpus]. 37 38[lzbench]: https://github.com/inikep/lzbench 39[Silesia compression corpus]: https://sun.aei.polsl.pl//~sdeor/index.php?page=silesia 40[gcc]: https://gcc.gnu.org/ 41 42| Compressor name | Ratio | Compression| Decompress.| 43| --------------- | ------| -----------| ---------- | 44| **zstd 1.5.1 -1** | 2.887 | 530 MB/s | 1700 MB/s | 45| [zlib] 1.2.11 -1 | 2.743 | 95 MB/s | 400 MB/s | 46| brotli 1.0.9 -0 | 2.702 | 395 MB/s | 450 MB/s | 47| **zstd 1.5.1 --fast=1** | 2.437 | 600 MB/s | 2150 MB/s | 48| **zstd 1.5.1 --fast=3** | 2.239 | 670 MB/s | 2250 MB/s | 49| quicklz 1.5.0 -1 | 2.238 | 540 MB/s | 760 MB/s | 50| **zstd 1.5.1 --fast=4** | 2.148 | 710 MB/s | 2300 MB/s | 51| lzo1x 2.10 -1 | 2.106 | 660 MB/s | 845 MB/s | 52| [lz4] 1.9.3 | 2.101 | 740 MB/s | 4500 MB/s | 53| lzf 3.6 -1 | 2.077 | 410 MB/s | 830 MB/s | 54| snappy 1.1.9 | 2.073 | 550 MB/s | 1750 MB/s | 55 56[zlib]: https://www.zlib.net/ 57[lz4]: https://lz4.github.io/lz4/ 58 59The negative compression levels, specified with `--fast=#`, 60offer faster compression and decompression speed 61at the cost of compression ratio (compared to level 1). 62 63Zstd can also offer stronger compression ratios at the cost of compression speed. 64Speed vs Compression trade-off is configurable by small increments. 65Decompression speed is preserved and remains roughly the same at all settings, 66a property shared by most LZ compression algorithms, such as [zlib] or lzma. 67 68The following tests were run 69on a server running Linux Debian (`Linux version 4.14.0-3-amd64`) 70with a Core i7-6700K CPU @ 4.0GHz, 71using [lzbench], an open-source in-memory benchmark by @inikep 72compiled with [gcc] 7.3.0, 73on the [Silesia compression corpus]. 74 75Compression Speed vs Ratio | Decompression Speed 76---------------------------|-------------------- 77 |  78 79A few other algorithms can produce higher compression ratios at slower speeds, falling outside of the graph. 80For a larger picture including slow modes, [click on this link](doc/images/DCspeed5.png). 81 82 83## The case for Small Data compression 84 85Previous charts provide results applicable to typical file and stream scenarios (several MB). Small data comes with different perspectives. 86 87The smaller the amount of data to compress, the more difficult it is to compress. This problem is common to all compression algorithms, and reason is, compression algorithms learn from past data how to compress future data. But at the beginning of a new data set, there is no "past" to build upon. 88 89To solve this situation, Zstd offers a __training mode__, which can be used to tune the algorithm for a selected type of data. 90Training Zstandard is achieved by providing it with a few samples (one file per sample). The result of this training is stored in a file called "dictionary", which must be loaded before compression and decompression. 91Using this dictionary, the compression ratio achievable on small data improves dramatically. 92 93The following example uses the `github-users` [sample set](https://github.com/facebook/zstd/releases/tag/v1.1.3), created from [github public API](https://developer.github.com/v3/users/#get-all-users). 94It consists of roughly 10K records weighing about 1KB each. 95 96Compression Ratio | Compression Speed | Decompression Speed 97------------------|-------------------|-------------------- 98 |  |  99 100 101These compression gains are achieved while simultaneously providing _faster_ compression and decompression speeds. 102 103Training works if there is some correlation in a family of small data samples. The more data-specific a dictionary is, the more efficient it is (there is no _universal dictionary_). 104Hence, deploying one dictionary per type of data will provide the greatest benefits. 105Dictionary gains are mostly effective in the first few KB. Then, the compression algorithm will gradually use previously decoded content to better compress the rest of the file. 106 107### Dictionary compression How To: 108 1091. Create the dictionary 110 111 `zstd --train FullPathToTrainingSet/* -o dictionaryName` 112 1132. Compress with dictionary 114 115 `zstd -D dictionaryName FILE` 116 1173. Decompress with dictionary 118 119 `zstd -D dictionaryName --decompress FILE.zst` 120 121 122## Build instructions 123 124`make` is the officially maintained build system of this project. 125All other build systems are "compatible" and 3rd-party maintained, 126they may feature small differences in advanced options. 127When your system allows it, prefer using `make` to build `zstd` and `libzstd`. 128 129### Makefile 130 131If your system is compatible with standard `make` (or `gmake`), 132invoking `make` in root directory will generate `zstd` cli in root directory. 133It will also create `libzstd` into `lib/`. 134 135Other available options include: 136- `make install` : create and install zstd cli, library and man pages 137- `make check` : create and run `zstd`, test its behavior on local platform 138 139The `Makefile` follows the [GNU Standard Makefile conventions](https://www.gnu.org/prep/standards/html_node/Makefile-Conventions.html), 140allowing staged install, standard flags, directory variables and command variables. 141 142For advanced use cases, specialized compilation flags which control binary generation 143are documented in [`lib/README.md`](lib/README.md#modular-build) for the `libzstd` library 144and in [`programs/README.md`](programs/README.md#compilation-variables) for the `zstd` CLI. 145 146### cmake 147 148A `cmake` project generator is provided within `build/cmake`. 149It can generate Makefiles or other build scripts 150to create `zstd` binary, and `libzstd` dynamic and static libraries. 151 152By default, `CMAKE_BUILD_TYPE` is set to `Release`. 153 154#### Support for Fat (Universal2) Output 155 156`zstd` can be built and installed with support for both Apple Silicon (M1/M2) as well as Intel by using CMake's Universal2 support. 157To perform a Fat/Universal2 build and install use the following commands: 158 159```bash 160cmake -B build-cmake-debug -S build/cmake -G Ninja -DCMAKE_OSX_ARCHITECTURES="x86_64;x86_64h;arm64" 161cd build-cmake-debug 162ninja 163sudo ninja install 164``` 165 166### Meson 167 168A Meson project is provided within [`build/meson`](build/meson). Follow 169build instructions in that directory. 170 171You can also take a look at [`.travis.yml`](.travis.yml) file for an 172example about how Meson is used to build this project. 173 174Note that default build type is **release**. 175 176### VCPKG 177You can build and install zstd [vcpkg](https://github.com/Microsoft/vcpkg/) dependency manager: 178 179 git clone https://github.com/Microsoft/vcpkg.git 180 cd vcpkg 181 ./bootstrap-vcpkg.sh 182 ./vcpkg integrate install 183 ./vcpkg install zstd 184 185The zstd port in vcpkg is kept up to date by Microsoft team members and community contributors. 186If the version is out of date, please [create an issue or pull request](https://github.com/Microsoft/vcpkg) on the vcpkg repository. 187 188### Visual Studio (Windows) 189 190Going into `build` directory, you will find additional possibilities: 191- Projects for Visual Studio 2005, 2008 and 2010. 192 + VS2010 project is compatible with VS2012, VS2013, VS2015 and VS2017. 193- Automated build scripts for Visual compiler by [@KrzysFR](https://github.com/KrzysFR), in `build/VS_scripts`, 194 which will build `zstd` cli and `libzstd` library without any need to open Visual Studio solution. 195 196### Buck 197 198You can build the zstd binary via buck by executing: `buck build programs:zstd` from the root of the repo. 199The output binary will be in `buck-out/gen/programs/`. 200 201### Bazel 202 203You easily can integrate zstd into your Bazel project by using the module hosted on the [Bazel Central Repository](https://registry.bazel.build/modules/zstd). 204 205## Testing 206 207You can run quick local smoke tests by running `make check`. 208If you can't use `make`, execute the `playTest.sh` script from the `src/tests` directory. 209Two env variables `$ZSTD_BIN` and `$DATAGEN_BIN` are needed for the test script to locate the `zstd` and `datagen` binary. 210For information on CI testing, please refer to `TESTING.md`. 211 212## Status 213 214Zstandard is currently deployed within Facebook and many other large cloud infrastructures. 215It is run continuously to compress large amounts of data in multiple formats and use cases. 216Zstandard is considered safe for production environments. 217 218## License 219 220Zstandard is dual-licensed under [BSD](LICENSE) OR [GPLv2](COPYING). 221 222## Contributing 223 224The `dev` branch is the one where all contributions are merged before reaching `release`. 225If you plan to propose a patch, please commit into the `dev` branch, or its own feature branch. 226Direct commit to `release` are not permitted. 227For more information, please read [CONTRIBUTING](CONTRIBUTING.md). 228
